"Limit selection to visible" not working
Oh that was a tricky one...

it's just because you have collapsed the actual horizontal bottom bar of your 3D window, and the one we see is actually from another 3D window that you also have collapsed

so grip the bottom of your 3D windows and pull it up, them display its real bottom menu bar with the small "+" on the bottom right

and now you can activate the Limit Selection to Visible button